You
can convert any cheap PC mouse into a Paddle controller, just
glue a plastic rod extension to the X axis wheel of your mouse,
drill a hole on the rear side of the mouse shell to allow the rod
extension (shown in White) to reach the outside, glue a plastic
knob on the outside, remove the rubber ball and stick a label
cover on the bottom to make sure no external light gets inside of
it.

I
used an empty ink cartdridge from a Bic pen as the Rod extension,
Krazy Glue to bond it and an old Genius Mouse model:Easy Mouse.
Took me 10 mins. to do it.

If
you use Z26 you can press the Tab key to invert the X axis
movement.

This
is the final result!

The
'knob' actually is a tire from a toy car, I liked it because the
surface is rugged and it has more grip to it, the 'knob' is
mounted on a screw that is glued to the plastic rod extension
inside. Works great!

Legal
Disclaimer: I won't be held responsible in any way and I won't be
held liable of any damage if you decide to build your own
controllers using these ideas shown here. I'm not related in any
way with Atari, Genius or any other company mentioned here. These
projects were made as a labour of love for Testing and
Educational Purposes only. They're shown 'as-is' without
warranty. In a few words: Use them under your own risk.